+Cc Matthew, again :)
On Thu, 2025-05-22 at 18:19 +0200, Christian König wrote:
> On 5/22/25 16:27, Tvrtko Ursulin wrote:
> >
> > On 22/05/2025 14:41, Christian König wrote:
> > > Since we already iterated over the xarray we know at which index
> > > the new
> > > entry should be stored. So instead of using xa_alloc use xa_store
> > > and
> > > write into the index directly.
> > >
> > > Signed-off-by: Christian König <christian.koe...@amd.com>
> > > ---
> > > drivers/gpu/drm/scheduler/sched_main.c | 12 ++++++------
> > > 1 file changed, 6 insertions(+), 6 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/scheduler/sched_main.c
> > > b/drivers/gpu/drm/scheduler/sched_main.c
> > > index f7118497e47a..d2d64bf17c96 100644
> > > --- a/drivers/gpu/drm/scheduler/sched_main.c
> > > +++ b/drivers/gpu/drm/scheduler/sched_main.c
> > > @@ -871,10 +871,8 @@ EXPORT_SYMBOL(drm_sched_job_arm);
> > > int drm_sched_job_add_dependency(struct drm_sched_job *job,
> > > struct dma_fence *fence)
> > > {
> > > + unsigned long index = -1;
> > > struct dma_fence *entry;
> > > - unsigned long index;
> > > - u32 id = 0;
> > > - int ret;
> > > if (!fence)
> > > return 0;
> > > @@ -896,11 +894,13 @@ int drm_sched_job_add_dependency(struct
> > > drm_sched_job *job,
> > > return 0;
> > > }
> > > - ret = xa_alloc(&job->dependencies, &id, fence,
> > > xa_limit_32b, GFP_KERNEL);
> > > - if (ret != 0)
> > > + entry = xa_store(&job->dependencies, index + 1, fence,
> > > GFP_KERNEL);
> >
> > From the code it looks index does not "move" for NULL slots?
>
> Correct, but I just found out that the macro initializes index to
> zero, so that approach also doesn't work.
>
> *sigh* going to look into this again tomorrow. It looks like this use
> case is somehow not well supported at all by xarray.
@Matthew, would be really nice if you could give some insights to that
and maybe give advice on a path how to best do that with xarray in a
canonical way.
Thanks,
P.
>
> Regards,
> Christian.
>
> >
> > That is, if someone:
> >
> > 1) Preallocates one entry, when trying to populate it index will be
> > -1 after xa_for_each?
> >
> > 2) Add one, preallocate one, then add one more - index will be 0
> > after xa_for_each?
> >
> > Regards,
> >
> > Tvrtko
> >
> > > + if (xa_is_err(entry))
> > > dma_fence_put(fence);
> > > + else
> > > + WARN_ON(entry);
> > > - return ret;
> > > + return xa_err(entry);
> > > }
> > > EXPORT_SYMBOL(drm_sched_job_add_dependency);
> > >
> >
>
